NPPB and pulmonary arterial hypertension: Efficacy included changes in the 6-min walk distance (6MWD), World Health Organization functional class (WHO-FC), N-terminal pro-brain natriuretic peptide (NT-proBNP) levels, hemodynamics, echocardiography and survival.<h4>Results</h4>Nine studies, consisting of 408 PAH patients, that met the inclusion criteria were included.